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Peugeot Citroen reveals fuel economy calculations

By raccars Published

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PSA Peugeot Citroen reveals exact methods used to calculate its real-world economy figures.

Earlier this year, real-world fuel consumption figures were revealed for 30 Peugeot Citroen cars. This figure is set to reach 50 by the end of this year and the PSA Group has now revealed the exact calculations which were used to come up with the figures.

The PSA Group, together with France Nature Environnement (FNE), Bureau Veritas, and Transport and Environment (T&E) emphasise that this is part of their collective commitment to increase transparency by publishing the test protocol and showing it to be a reliable method of assessment using a robust and scientific approach.

A reliable approach to fuel economy testing?

The protocol for calculating real-world fuel consumption dictates the methods, such as measurement and processing, and the means and the necessary equipment required to systematically calculate fuel consumption averages for typical customers. The protocol can be broken down into three steps; the selection and checking of a vehicle; the driving of the chosen vehicle and the measurement; and the processing of the results of the measurement.

The measurements need to be taken whilst a car has an amateur (i.e. non-professional) driver at the wheel and are conducted on public roads which are open to traffic. Driving conditions equating to real life must also be applied, with the inclusion of normal road gradients and the use of typical luggage and passenger loads and air-conditioning systems.

By the time 2016 ends there will be 50 models with their real-world fuel consumption figures displayed on the website of the Peugeot Citroën brands, together with a customer simulator that can help to predict fuel consumption depending on conditions and driving style. Next year, Bureau Veritas, France Nature Environnement, Transport & Environment and the PSA Group will also use a similar procedure in terms of the measurement of nitrous oxide emissions in the real world.

Peugeot Citroen claims testing is an 'inspiration'

The PSA Group’s executive vice president for quality and engineering, Gilles le Borgne, said that the protocol has resulted from a successful and ‘unprecedented’ collaboration between NGOs, a certification organisation and a manufacturer and should be seen as an inspiration for others when it comes to offering customers transparency.

Transport & Environment’s clean vehicles director, Greg Archer, meanwhile, said that the real-word protocol offers ‘more representative’ data to customers than lab-based testing, ensuring that they have a better chance of choosing the best cars for their own usage patterns in terms of fuel efficiency. He added that this scientific approach was ‘reproducible’ and ‘robust’, as well as being reliable for the measuring of real carbon emissions. He went on to urge all car manufacturers and the European Commission to make use of the real-world test for both advertising and regulatory purposes.

Problems with the official test

PSA has been one of a group of vehicle manufacturers which have spoken out about the official NEDC test for fuel economy, saying that unrealistic MPG figures are being generated. The test, known as the NEDC, or New European Diving Cycle, is currently used to calculate the official CO2 and MPG data for every new car which goes on sale in the European market.

The test which is carried out using a rolling road has been widely criticised for failing to take into account real-life driving conditions, including driving styles, weather conditions and other traffic. The test was also developed before electric and hybrid vehicles became commonplace and is known to produce unrealistic CO2 and fuel economy figures for some cars including the Mitsubishi Outlander PHEV.

PSA Peugeot Citroen, therefore, has announced that it will now use real-world testing as well as the required NEDC tests and that it will publish the findings.

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